package config_test

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"sourcecraft.dev/bigbes/lethe/internal/config"
)

// validForwardAuthYAML is a baseline valid configuration with forward-auth
// enabled. Tests typically clone and tweak this string for negative cases.
const validForwardAuthYAML = `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice", "bob"]
  admins: ["alice"]
  forward_auth:
    enabled: true
  oidc:
    enabled: false
logging:
  level: "info"
  format: "tint"
ingest: {}
`

const validOIDCYAML = `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: false
  oidc:
    enabled: true
    issuer: "https://auth.example.com"
    audience: "lethe"
logging:
  level: "info"
  format: "tint"
ingest: {}
`

const validBothEnabledYAML = `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: true
  oidc:
    enabled: true
    issuer: "https://auth.example.com"
    audience: "lethe"
logging:
  level: "info"
  format: "tint"
ingest: {}
`

func writeYAML(t *testing.T, body string) string {
	t.Helper()
	dir := t.TempDir()
	path := filepath.Join(dir, "config.yaml")
	if err := os.WriteFile(path, []byte(body), 0o600); err != nil {
		t.Fatalf("write yaml: %v", err)
	}
	return path
}

func TestLoad_ValidForwardAuth(t *testing.T) {
	path := writeYAML(t, validForwardAuthYAML)
	cfg, err := config.Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if cfg.Server.Bind != "127.0.0.1:8080" {
		t.Errorf("Server.Bind = %q", cfg.Server.Bind)
	}
	if !cfg.Auth.ForwardAuth.Enabled {
		t.Error("ForwardAuth.Enabled = false, want true")
	}
}

func TestLoad_ValidOIDC(t *testing.T) {
	path := writeYAML(t, validOIDCYAML)
	cfg, err := config.Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if !cfg.Auth.OIDC.Enabled {
		t.Error("OIDC.Enabled = false, want true")
	}
	if cfg.Auth.OIDC.Issuer != "https://auth.example.com" {
		t.Errorf("OIDC.Issuer = %q", cfg.Auth.OIDC.Issuer)
	}
}

func TestLoad_ValidBothEnabled(t *testing.T) {
	path := writeYAML(t, validBothEnabledYAML)
	if _, err := config.Load(path); err != nil {
		t.Fatalf("Load: %v", err)
	}
}

func TestLoad_Defaults(t *testing.T) {
	path := writeYAML(t, validForwardAuthYAML)
	cfg, err := config.Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	if cfg.Auth.ForwardAuth.UserHeader != "Remote-User" {
		t.Errorf("ForwardAuth.UserHeader = %q, want Remote-User", cfg.Auth.ForwardAuth.UserHeader)
	}
	if cfg.Auth.OIDC.UsernameClaim != "preferred_username" {
		t.Errorf("OIDC.UsernameClaim = %q, want preferred_username", cfg.Auth.OIDC.UsernameClaim)
	}
	if cfg.Ingest.MaxBodyBytes != 16*1024*1024 {
		t.Errorf("Ingest.MaxBodyBytes = %d, want %d", cfg.Ingest.MaxBodyBytes, 16*1024*1024)
	}
	if cfg.Ingest.MaxTurnContentBytes != 4*1024*1024 {
		t.Errorf("Ingest.MaxTurnContentBytes = %d, want %d", cfg.Ingest.MaxTurnContentBytes, 4*1024*1024)
	}
	if cfg.Ingest.ChunkSize != 500 {
		t.Errorf("Ingest.ChunkSize = %d, want 500", cfg.Ingest.ChunkSize)
	}
	if cfg.Database.BusyTimeout != 5*time.Second {
		t.Errorf("Database.BusyTimeout = %s, want 5s", cfg.Database.BusyTimeout)
	}
	if cfg.Server.ShutdownGrace != 10*time.Second {
		t.Errorf("Server.ShutdownGrace = %s, want 10s", cfg.Server.ShutdownGrace)
	}
}

func TestLoad_EmptyAllowlistRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: []
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error for empty allowed_users, got nil")
	}
}

func TestLoad_NonLoopbackBindRejected(t *testing.T) {
	body := strings.Replace(validForwardAuthYAML, `"127.0.0.1:8080"`, `"0.0.0.0:8080"`, 1)
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error for non-loopback bind, got nil")
	}
}

func TestLoad_BothAuthModesDisabledRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: false
  oidc:
    enabled: false
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error when both auth modes are disabled, got nil")
	}
}

func TestLoad_OIDCEnabledWithoutIssuerRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: false
  oidc:
    enabled: true
    audience: "lethe"
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error for OIDC enabled without issuer, got nil")
	}
}

func TestLoad_OIDCEnabledWithNonURLIssuerRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: false
  oidc:
    enabled: true
    issuer: "not a url"
    audience: "lethe"
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error for non-URL issuer, got nil")
	}
}

func TestLoad_AdminNotInAllowedUsersRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  admins: ["mallory"]
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error when admin is not in allowed_users, got nil")
	}
}

func TestLoad_EmptyAdminsAccepted(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  admins: []
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err != nil {
		t.Fatalf("expected empty admins to be accepted, got %v", err)
	}
}

func TestLoad_MissingDatabasePathRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database: {}
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error for missing database.path, got nil")
	}
}

func TestLoad_MaxTurnContentBytesGreaterThanMaxBodyBytesRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest:
  max_body_bytes: 1024
  max_turn_content_bytes: 4096
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error when max_turn_content_bytes > max_body_bytes, got nil")
	}
}

func TestLoad_UnknownYAMLKeyRejected(t *testing.T) {
	body := `
server:
  bind: "127.0.0.1:8080"
  totally_unknown_key: 42
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	if _, err := config.Load(writeYAML(t, body)); err == nil {
		t.Fatal("expected error for unknown YAML key, got nil")
	}
}

func TestLoad_EnvOverride(t *testing.T) {
	// Use a YAML body without admins so the override test only exercises
	// the slice-decoding path (LETHE_AUTH_ALLOWED_USERS overrides YAML).
	body := `
server:
  bind: "127.0.0.1:8080"
database:
  path: "./lethe.db"
auth:
  allowed_users: ["alice"]
  forward_auth:
    enabled: true
logging:
  level: "info"
  format: "tint"
ingest: {}
`
	path := writeYAML(t, body)
	t.Setenv("LETHE_AUTH_ALLOWED_USERS", "carol,dave")
	cfg, err := config.Load(path)
	if err != nil {
		t.Fatalf("Load: %v", err)
	}
	got := cfg.Auth.AllowedUsers
	if len(got) != 2 || got[0] != "carol" || got[1] != "dave" {
		t.Errorf("AllowedUsers = %v, want [carol dave]", got)
	}
}

func TestMustLoad_PanicsOnError(t *testing.T) {
	defer func() {
		if r := recover(); r == nil {
			t.Fatal("expected MustLoad to panic on missing file")
		}
	}()
	config.MustLoad("/nonexistent/path/that/should/not/exist.yaml")
}